Field of the Invention
The present invention relates to a projection zoom lens and an image projection apparatus, and more particularly, to a projection zoom lens which is suitable for enlarging and projecting a display image of an image display element such as a digital micromirror device or a liquid crystal display (LCD) onto a screen, and an image projection apparatus including the same.
Description of the Related Art
In a three-panel type projector, an axial chromatic aberration can be suppressed by adjusting the position of the image display element. In contrast, in a single-panel type projector, because the position of the image display element is defined, it is necessary to correct the axial chromatic aberration in the projection zoom lens. In addition, with regard to aberrations other than axial chromatic aberration, it is required to satisfactorily correct aberrations with miniaturization of the image display element. Therefore, in order to achieve a high performance, a projection zoom lens using a glass material with a high refractive index for a positive lens in the vicinity of an aperture is disclosed in JP 2008-52174 A.
However, in the projection zoom lens described in JP 2008-52174 A, it is difficult to cope with the high definition of the image display element mounted on the recent image projection apparatus. That is, since the required performance of the axial chromatic aberration becomes higher, it is difficult to achieve a sufficient axial chromatic aberration correction in the technique described in JP 2008-52174 A.